The earliest recollection of this bug is traced back to PAN-OS 10.1.9 - July 22, 2025. This bug is fixed in PAN-OS versions 10.2.4, 10.1.9, 9.1.18, 11.0.1. Fixed an issue where an external dynamic list fetch failed with the error message Unable to fetch external dynamic list. Couldn't resolve host name. Using old copy for refresh . For more information: https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-9-known-and-addressed-issues/pan-os-10-1-9-addressed-issues https://docs.paloaltonetworks.com/pan-os/10-2/pan-os-release-notes/pan-os-10-2-4-known-and-addressed-issues/pan-os-10-2-4-addressed-issues https://docs.paloaltonetworks.com/pan-os/11-0/pan-os-release-notes/pan-os-11-0-1-known-and-addressed-issues/pan-os-11-0-1-addressed-issues https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-addressed-issues/pan-os-9-1-18-addressed-issues